Exhaust-manifold muffler



Patented Jan. l, 1929.

UNITED STATES PATENT OFFICE.

SAMUEL A. STRANAHAN, OF FLINT, MICHIGAN, ASSIGNOR TO GENERAL MOTORS COR- PORATION, 0F DETROIT, MICHIGAN, A CORPORATION OF DELAWARE.

EXHAUST-MANIFOLD MUFFLER.

Application led February 28, 1927. Serial No. 171,709.

This invention relates to internal combustion engines and particularly to silencers or muflers for the purpose of dainpening and quieting the exhaust from the explosion chambers.

The object of the invention is to provide an improved device of simple construction for the purpose of minimizing noises due to discharge of spent products of combustion.

A further object is to provide an auxiliary muffler, located adjacent the discliargeports of the engine, to break up the sharp explosions and diffuse the draft of spent gas and allow their expansion, without the production of any appreciable back pressure, before the gases enter and pass thru the exhaust conduit leading to the regular concussion muffler, thereby eliminating drumming noises in the exhaust conduit.

Other object-s and advantages will be apparent from the following specification taken in connection with the accompanying drawing of a preferred embodiment of the invention, and wherein Figure 1 is a side elevation, illustrating a multi-cylinder engine mounted on the chassis frame of a motor vehicle, with the present muflling arrangement applied thereto; Figure 2 is a vertical sectional view of the auxiliary silencer, and Figure 3 is a transverse section taken on line 3-3 of Figure 2.

Referring to the drawing, the reference character 1 indicates one of the longitudinal side members of a vehicle chassis frame and a 2 is a multi-cylinder, internal combustion engine, supported upon the chassis frame. Fuel is supplied to the combustion chamber of the engine, by means of the intake manifold 3 and the spent gases are discharged from the combustion chamber into the exhaust inanifold 4, as will be readily understood. In the event it is desired to utilize exhausted gas to preheat the fresh fuel, a dependent jacket 5 of the exhaust manifold may be provided to surround the fuel intake pipe 6. To secure circulation of hot gases thru the jacket 5, a conduit 7 is connected to the lateral spur 8 of a T-coupling 9, between the discharge end of the exhaust manifold and the auxiliary muffler or dampener 10. A pivoted valve 1l may be provided adjacent the discharge end of the exhaust manifold to control the amount of gases to be by-pas'sed thru the jacket 5 and conduit 7, the valve being actuated either manually or automatically, as for instance,

by means of a therinostatic 'element 12 in the exhaust manifold 4. Annular flanges at the opposite ends of the T-coupling 9 are bolted respectively to the exhaust manifold 4 and muffler 10. lroheating of the fuel charge is amore or less common practice in automotive engine design and the arrangement shown is one of conventional foi'in. Not being a part of the present invention, the arrangement to preheat the fuel may be entirely omitted, in which case t-lie exhaust manifold and auxiliary muffler would be directly connected with each other.

The .niufiler or dainpener 10, is shown as consisting of a vcylindrical casing 13 having at the inlet end, an annular head or ring 14 carrying a uniformly tapering tubular passageway or conical nozzle 15, which extends coaxially thru the casing 13, and slightly beyond a. frusto-conical baffle wall 16, which in turn is secured at its periphery oi' base to the casing 13. The central opening at the smaller end-of the frusto conical wall 16, is slightly larger than that portion of the nozzlc surrounded by the end of the wall, affording a clearance or passageway therebetween. The walls of the conical tube 15 and casing 13, are spaced from each other to afferd an expansion chamber 17, and both the conical tube l5 and baffle 16 are perforated, to permit passage of gases into and out ofthe expansion chamber 17. At the outlet end of the casing 13, is located an elbow fitting 18, having an annular flange at the end thereof, to which is bolted the fiange of a coupling 19, on the end of the exhaust conduit 20. The exhaust conduit 20 leads along the chassis fiame, a considerable distance to the rear, where the customary detonation mufiler 21 is provided to completely quiet down the noises, permitting the gases to freely expand and noiselessly escape to atmosphere thru the final discharge pipe 22.

It will readily be seen, that when the draft of spent gases leaves the exhaust manifold 4, an immediate diffusion and expansion occurs, Which dampens the sharp explosions and obviates drumming noises in the exhaust conduit 20.. A portion of t-lie spent gases rushing thru the tapering passageway 15, are diverted thru the lat-eral pcrforations and into the expansion chamber 17, materially relieving the pressure, while the gases passing out the small end of the nozzle 15, induce a artial vacuum about the outside of the nozz e to withdraw gases in the ex ansion chamber, past the frusto-conical ba e wall 16, the flow then proceeding thru the exhaust conduit 2O to the muiiler 21. The tapering wall of the baille 16 results in a tendency for the gases to crowd to the center and pass the baiile thru the central opening at the smaller end of the baiie, whereby a slight additional vacuum is created about the outside of the wall to draw some of the gases thru the p'erforations and further breakup the draft. Thus the draft of exhaust gases passes rapidly thru, and is thorspaced relation therewith, the space between the walls of passageway and casing forming an expansion chamber, the wall of the passageway being provided with lateral perforations to establish communication between the interior of the passageway and expansion chamber, and a `truste-conical perforate baiiie wall secured at its periphery to the casing-and arranged coaxially of the passageway and having a central opening thru .which the smaller end of .the passageway projects to a point slight'- ly beyond the battle wall, said central opening being of larger diameter than that portion of .the passageway extending therethru 'to afford an outlet opening at the smaller end of the frusto-conical wall.

2. In a device of the character described,

a cylindrical casing, a conical tubular passageway extending axially thru the casing in spaced relation with the walls of the casmg, forming thereby an expansion chamber communicating with the passageway by means of perforations in the wall of the passageway, the direct flow of gases thru the conical passageway creating a partial vacuum at the outlet, and a conical baille wall co-axially arranged in said casing and having' perforations therein and an opening at the end thereof through which opening said tubular passageway projects to a point beyond the wall,

the direct How of gases thru the opening creat- 4 ing partial vacuum to augment that created at the outlet of the conical passageway to Withdraw' the gases in the expansion chamber.

3. In a device of the characterdescribed, a cylindrical casing, aI truste-conical baiile wall secured at its base to the wall of the casing, a perforate conical tube secured at its base at the inlet to said casing and projecting through an opening in the ba-ile wall toa point therebeyond, whereby the flow of gases through the outlet of said tube serves t0 draw gases past the baiile wall.

In testimony whereof I aliix my signature.

SAMUEL A. STRANAI-IAN. 

